Many types of magnetic bearings and active magnetic bearings exist. An active magnetic bearing (AMB) works on the principle of electromagnetic attraction and/or repulsion and may consist of an electromagnet assembly, a set of power amplifiers that supply current to the electromagnets, a controller, and gap sensors with associated electronics to provide the feedback required to control the position of the rotor within the gap. AMBs may be radial or axial in orientation. Both types of magnetic bearings may experience vibrations, which vibrations may be a result of rotor resonance.
EP 2187075 provides one example of a magnetic bearing, and EP 1504201 discloses a dynamically stabilizing magnetic bearing, both of which patents are incorporated by reference herein in their entireties.
U.S. Pat. Nos. 4,935,838 and 6,099,165 disclose various vibration controllers for rotary machinery, both of which patents are incorporated by reference herein in their entireties.